In many sports, such as golf, tennis, and baseball, the grip pressure applied by the athlete to the club, racket, or bat, is crucial to the player's accuracy and success. Thus, devices that provide athletes feedback regarding their grip are often considered useful for optimal game play.
Some existing athlete's gloves, such as SensoGlove® (at the time of this writing, for the following goods: sports or athletic glove, namely, glove used with swinging sporting equipment in the fields of baseball, hockey, tennis racquetball, and golf.) which is used for golfers, include pressure sensors located against the fingertips of the wearer of the glove. The pressure sensors include pressure transducers which output an electrical signal proportionate to the pressure applied by the user's fingers, and notify the user of the pressure used on a scale of 1-18. However, the measurements made by SensoGlove are based solely on the pressure applied by the user's fingers to the golf club, and do not take into consideration the physiological activity and/or tension in other muscles in the user's hand, which may have a great impact on the accuracy of play. Specifically, pressure sensor typically measure forces applied perpendicular to the sensor, and may overlook the effects of forces that are off-axis to the measuring surface, thereby providing information which is not sufficiently accurate for helping an athlete reach their optimal play ability. Additionally, the readings of a pressure sensor may be impacted by the length of the user's fingers, because longer fingers generate higher leverage forces and thus the leverage forces and the pressure applied may vary between different people, making it hard for a glove using pressure sensors to be suitable for different athletes.
Surface electromyography (EMG) is a method for recording bio-electrical signals of a muscle's activity by placing electrodes or other contact points on the skin adjacent the muscle. Existing EMG based devices for measuring grip pressure place the electrodes on the user's forearm and/or shoulder, and use the readings from muscles in these locations to determine the pressure applied to the item in the athlete's hands. However, placement of a device on the user's forearm or shoulder is likely to impede the user's range of motion, thus adversely affecting their ability to swing a golf club, baseball bat, or tennis racket.
Thus, there is a need for an EMG based device providing feedback to a user from the muscles of the hand, using electrodes. However, the challenge was where to place the electrodes/sensors on a hand in order to record the meaningful EMG signals during a series of very fast sequential hand movements.